1. Field of the Invention
The prevent invention relates to a sliding member and a method of manufacturing the same and, specifically, relates to an epoxy resin-based sliding member having a low friction coefficient and a method of manufacturing the same.
2. Description of Related Art
In the related art, in an internal combustion engine such as an engine or the like of an automobile, sliding members are used for various units including a piston skirt portion. Regarding these sliding members, various techniques have been developed in order to comply with, for example, CAFE standards for global environmental protection which state that energy loss is reduced through a reduction in friction coefficient.
On the other hand, along with changes in operation conditions which are frequently changed from engine start to constant-speed driving (that is, high-speed driving) through acceleration, a lubrication state between the units and members in contact with the units is shifted from a solid lubrication region during engine start to a boundary lubrication region (also referred to as “boundary region”) during acceleration and is further shifted from the boundary region to a liquid lubrication region (also referred to as “liquid region”) during constant-speed driving. It is necessary that a sliding member of an internal combustion engine such as an engine of an automobile satisfy not only properties required in the solid lubrication region and the boundary lubrication region but also properties required in the liquid lubrication region. That is, in the solid lubrication region, scuffing in which an unpleasant sound (for example, a rasping sound) is produced by collision between the units and other members in contact with the units needs to be suppressed; and in the liquid lubrication region, superior slidability is required. Therefore, for a sliding member, a film formed thereon needs to have heat resistance, and a reduction in the friction coefficient is required in the respective regions, in particular, in the solid lubrication region and the boundary lubrication region in which the lubrication state is unstable. As a sliding member satisfying these requirements, a DLC-based sliding member in which DLC is used as a film is proposed.
For example, Japanese Patent Application Publication No. 2004-278705 (JP 2004-278705 A) discloses a sliding member including: a hard carbon film that is a sliding surface; and a concave portion in which the depth distribution from the center of to an end portion of a direction, which is perpendicular to a sliding direction of the sliding surface, changes depending on the thickness distribution of an oil film. As a specific example, a sliding member including a hard carbon film, which is formed on a substrate surface by magnetron sputtering in which carbon is a target, is disclosed.
However, in the above-described technique of the related art, it is necessary to use a physical vapor deposition method for forming the DLC film. Therefore, productivity is low, high costs are inevitable, and thus it is difficult to obtain a sliding member having high productivity and a low friction coefficient.